Optical lenses are employed in a variety of devices for many purposes such as modifying focus and magnification. Many conventional devices that employ optical lenses use lenses that are made from solid materials, such that the optical properties of the lenses (e.g., their focal distances) remain constant or nearly constant over time. For example, eyeglasses used for vision correction typically are made of solid materials such as glass and plastic. Similarly, cameras and other optical systems such as microscopes, video monitors, video recorders, copy machines, scanners, etc., commonly employ solid lenses.
Although lenses made from solid materials generally maintain their optical properties over time, the use of such lenses also has numerous disadvantages. With respect to vision correction lenses, for example, the power of vision correction is fixed at the time of fabrication of the lenses. As a consequence, today's eyeglass lenses often cannot be mass produced at low cost because the lenses are specially fabricated for each and every patient. Since each patient has his/her unique power requirement for eye correction, the patient has to see an ophthalmologist or optometrist to measure his/her eye correction power first before having the vision correction lenses fabricated. In addition, machining glass or plastic material to the precise shape of a lens according to a prescription is, by itself, a relatively high-cost and low throughput process. Often, it takes several days or even weeks for patients to receive a new pair of eyeglasses. In comparison with certain off-the-shelf vision products such as sunglasses, vision-correcting eyeglasses designed and fabricated using current technology are particularly expensive and complicated to manufacture.
Further, vision correction lenses used in today's eyeglasses do not have the flexibility to handle various situations with which wearers are often confronted. For example, the optimal eye correction for a given individual frequently varies depending upon a variety of factors, such as the person's age, the person's lifestyle, and various practical circumstances. Consequently, an adult typically needs to replace his or her eye correction lenses every few years. For juveniles or adolescents, updating of vision correction eyeglasses often is required more frequently than for adults.
For certain persons, particularly persons in their 50s and over, the vision correction that is needed for viewing near objects can be very different from the vision correction that is needed for viewing distant objects. To provide different levels of vision correction via a single pair of eyeglasses, many of today's eyeglasses employ bifocal lenses (or even tri-focal or otherwise multi-focal lenses), in which different sections of a given lens provide different optical properties. Yet such bifocal lenses offer at best an inconvenient solution to the problem of how to provide varying levels of vision correction on a single pair of eyeglasses. Traditionally, bifocal lenses are formed from pairs of lens portions that are positioned or fused adjacent to one another along a midline of the overall lens. Because the midline between the lens portions is a perceptible boundary between the lens portions, such lenses are often cosmetically undesirable.
Although newer bifocal lenses are available that are not as cosmetically undesirable, insofar as the lenses are graded such that there is only a gradual change of correction power from region to region on the lens and such that a clear boundary separating different regions of the lens does not exist, such newer bifocal lenses nevertheless share other problems with traditional bifocal lenses. In particular, because different portions of the lenses have different vision correction characteristics, the wearer's field-of-view at any given time or circumstance via the lenses is still compromised insofar as only certain portions of the lenses provide the appropriate optical characteristics for the wearer at that time/circumstance.
Additionally, while many persons do not require bifocal lenses, these persons can nevertheless prefer that their eyeglasses provide different amounts of vision correction in different situations. For example, the preferred amount of vision correction for a person when driving a car or watching a movie can differ from the preferred amount of vision correction for that person when reading a book or working in front of a computer screen.
For at least these reasons, therefore, it is apparent that the use of solid lenses with fixed optical properties in eyeglasses is disadvantageous in a variety of respects. Yet the disadvantages associated with using solid lenses with fixed optical properties are not limited to the disadvantages associated with using such lenses in eyeglasses/eyewear. Indeed, the use of solid lenses with fixed properties in a variety of devices such as cameras, microscopes, video monitors, video recorders, copy machines, scanners, etc. also presents similar disadvantages.
Further, the use of solid lenses with fixed optical properties entails additional disadvantages in systems that employ combinations of lenses that interact with one another to provide overall optical properties. Such systems include, for example, zoom lens systems in which two or more optical lenses of fixed optical properties are moved relative to one another to change optical properties of the overall combination of lenses forming the zoom lens. Because the optical properties of the individual lenses used in such systems are fixed, the overall optical properties of the combinations of lenses depend upon other factors, particularly the relative positioning of the individual lenses. Consequently, to provide the desirable features and capabilities associated with systems such as zoom lens systems, complicated and expensive mechanical and/or other components and techniques must be employed to achieve the desired effects.
In particular with respect to zoom lens systems, conventional systems with zooming capabilities are typically more expensive and often more bulky/heavy than systems without such capabilities. The most important figure of merit for zoom lenses is the zoom ratio. The higher the zoom ratio is, the more costly the system becomes. A typical camera has an optical zoom ratio of about 3, and some high-end imaging systems have a zoom ratio of greater than 10. Currently, all optical zoom lenses achieve zoom-in and zoom-out functions by changing the distance(s) between the individual lenses forming the overall zoom lens. This involves high-precision mechanical motions of the lenses over a typical range of several centimeters. To provide highly-precise, reliable relative movement of the lenses typically requires a mechanical system that is complicated, slow, bulky and expensive.
The need to vary lens distance to achieve zooming has become a roadblock for incorporating zooming features into many new and emerging applications. Many modern “electronic gadgets” including cell phones, personal digital assistants (PDAs), and notebook computers are equipped with CCD or CMOS cameras. Implementation of cameras into such gadgets has evolved from being a novelty to being a standard feature, and many such gadgets now support imaging-related functions that involve not just imaging but also recording, videophone capabilities, and video conferencing. Yet conventional zoom lenses are difficult to incorporate into these small electronic gadgets and their optical devices.
Therefore, it would be advantageous if one or more new types of lenses and/or lens systems could be developed that alleviated the disadvantages associated with using solid lenses having fixed optical properties as discussed above. In particular, it would be advantageous if a new type of lens or lens system could be developed for implementation in eyeglasses that made it possible to easily and inexpensively adjust optical characteristics of the eyeglasses without entirely replacing the lenses. It would further be advantageous if the optical characteristics of the lenses could be flexibly varied over a wide spectrum, rather than simply to a limited number of discrete levels. It additionally would be advantageous if variations in the optical properties of a lens could be applied to the entire lens, so that, for example, variations in the optical properties of the lens would apply to an entire range of vision of a wearer of eyeglasses employing the lens, rather than merely a portion of that range of vision.
It further would be advantageous if the new type of lens or lens system could also or alternatively be implemented in other systems that employ lenses such as cameras, microscopes, video monitors, video recorders, optical recording mechanisms, surveillance equipment, inspection equipment, agile imaging equipment, target tracking equipment, copy machines, scanners, etc. It additionally would be advantageous if the new type of lens or lens system could be implemented in zoom lens systems in a manner that reduced the need for complicated mechanical systems for controlling relative positioning of multiple lenses within the zoom lens systems. It also would be advantageous if a zoom lens system employing the new type of lens or lens system could be compactly implemented on one or more types of physically small “electronic gadgets” such as cell phones, personal digital assistants (PDAs), or notebook computers.